I got sidetracked yesterday at the range helping a range buddy with a problem with his AR and didn’t finish the loads I had laid out for the 12 FV 6.5mm Creedmoor. I went back to the range this morning and finished the last load.
The following are the results for the morning of May 7th shot in Northern Virginia at 100 yards. Temperatures from 64 to 70 degrees with winds from 3 to 5 mph. Altitude of the range is 250 feet above sea level.
All rounds were shot with a Savage 12 FV using Lapua brass and CCI BR-4 primers and all bullets were loaded to achieve a 1.361 msec. exit time that should be the sweet spot for a 26-inch 3% carbon steel barrel for the 12th reflection at the chamber.
# Grps Load Description Bullet Wgt- Vel-- Avg-- Median- Std Dev-- 1----- 2----- 3----- 4 4 IMR4350 41.4 gr 2.864 1.909 wf 1.361 * 64/65 deg. F. Sierra Tipped Match King #7430 130 2721 0.352 0.348 0.019 0.333 0.343 0.352 0.378
The results to date with the two powders used so far are:
Powder Avg Median St Dev IMR4350 0.376 0.376 0.062 IMR4451 0.397 0.400 0.079 Here is an update on the two different torque settings:
Torque on Action Screws Avg Median St Dev 3 Gps 35 In.-Lbs. 0.378 0.374 0.069 56 45 In.-Lbs. 0.438 0.456 0.071 12 Overall Average 0.388 0.381 0.073 68
When you compare the data for powders including torque settings, the numbers look a bit different.
Torque Powder Avg Median St Dev # Grps Diff. 35 IMR4350 0.376 0.376 0.062 28 35 IMR4451 0.379 0.368 0.077 28 0.67% 45 IMR4451 0.438 0.456 0.071 12 16.35%
The overall average of all groups has dropped from 0.391 to 0.388, but the average for IMR4451 with the 35 in.-lbs. torque setting has dropped to 0.379 (less than 1% difference to IMR4350) compared to the average of 0.438 for the 45 in.-lbs. torque setting with a 16.5% difference to IMR4350 and a 15.57% difference to the 35 in.-lbs. torque results for IMR4451 powder.
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